This application is based on Japanese Patent Application No. 2009-061636 filed with the Japanese Patent Office on Mar. 13, 2009, the entire content of which is hereby incorporated by reference.
1. Technical Field
The present invention relates to a displacement sensor with a confocal optical system, in which a displacement of a measurement object is measured in a noncontact manner and obtains an image around a measuring point.
2. Related Art
Conventionally, for example, as disclosed in Japanese Patent No. 3513817, the displacement sensor in which the confocal optical system is used includes an imaging device that takes an image of an object whose displacement is measured thereby.
Specifically as illustrated in FIG. 16, the displacement sensor includes a light source 901 that emits light to an object to be measured 900, an imaging light source 913 that emits light having a wavelength different from that of the light emitted from the light source 901 to the object to be measured 900, an objective lens 906 through which the reflected light of the light source 901 from the object to be measured 900 and the reflected light of the imaging light source 913 from the object to be measured 900 pass, a beam splitter 905 to which each pieces of reflected light passing through the objective lens 906 is incident, an imaging device 909 that takes an surface image of the object to be measured with the light reflected from the beam splitter 905, a light receiving device 902 that receives light transmitted through the beam splitter 905, the light being the light reflected from the object to be measured 900, and a beam splitter 903 that leads the light transmitted through the beam splitter 905 to the light receiving device 902.
In the displacement sensor, the objective lens 906 is oscillated with predetermined amplitude using an excitation coil, and the imaging device 909 takes an image in a position of the objective lens 906, in which a light receiving amount becomes the maximum in the light receiving device 902. Therefore, the imaging device 909 can take the image when the light is collected onto the surface of the object to be measured 900.
However, in the conventional displacement meter, when irregularity exists in the surface of the object to be measured 900 as illustrated in FIG. 16, the image that is taken with the imaging device 909 at the time the light is collected on the surface of the object to be measured becomes the image that is out of focus at levels except the displacement measuring point as illustrated in FIG. 17.
In the displacement sensor, there is a demand for a function of being able to confirm the measuring point using the clear image within the measurement range in the irregular object to be measured.